As always, this is based on my experiences fighting Mu. Results depend, and if you see something wrong, please say so.
I hate this match-up with a burning, bloody passion, and not just because Mu is another version of Noel.
Thankfully, a dedicated Tager only needs to get in close once to win a round, and I've found a couple of openings.
If a Mu player attempts to open a round with 5C>6C, Instant block the 5C and sledge through the 6C. From there, you can go into a few different combos, though a B. Sledge>2B>2C>Atomic Collider>Ender is your best option.
Divine Wrath of the Heavens is easily sledged through, and a sloppy Mu will either try to use it to get closer or as a way to deal some quick damage. Properly timed and spaced, a Sledge can be your best friend or your worst mistake. Keep an eye out for chances to hit a Mu using Totsuka Blade to approach, too, preferably after it's bounced off the last Steins Gunner.
Remember, the Steins Gunner shots won't curve. Timing a super-jump and barrier blocking during the fall can close distance on a Mu...or it can give her an opportunity to slip past.
Bait Origins just like any DP, and punish accordingly.
DO NOT ATTEMPT TO COUNTERATTACK DURING DIVINE WRATH OF THE HEAVENS. I've made this mistake several times, automatically seeing an opening and going for it. I'll be damned if that move isn't one gigantic invulnerability frame.
I've only lost to one Mu since the update, and that's because I underestimated one of her greatest assets; Sword of Decimation. This little number can be used to set back any progress you've made getting Mu into the corner, and is almost as annoying as Origins.
It might not be as ridiculous as it used to be, but this match-up still goes heavily in Mu's favor. Still, be patient, look for those opportunities to close in, watch your opponent for mistakes,
**Edited, thank you for pointing that out. I appreciate it.